(1) Field of the Invention
This invention relates to an improvement on a floating frame member for use in a fish breeding apparatus having a variety of favorable properties.
(2) Description of the Prior Art
In the fish breeding apparatus demarcating the sea with a net which is used for breeding or catching and preserving the fish and shellfish in the interior of the net, the net is hung and supported by a frame body floating on the surface of the sea. In order to enhance the efficiency in breeding or catching and hauling, it is necessary to provide a fish breeding apparatus having a large breeding capacity, particularly a larger plane projection area of the fish breeding apparatus.
However, to this end, a large-scale fish breeding apparatus is constituted by interconnecting a plurality of reinforced hoses each having a strain reinforcing layer embedded therein by means of straight couplings in such a way that the reinforced hoses may be curved to form a substantially circular form of as much as 30-100 m in diameter in its plane projection profile. It is possible to realize a large breeding capacity of 6-70 times larger than that of the fish breeding apparatus constituted by the rigid frame body, say, the steel pipes and the like. However, when the frame body of the former fish breeding apparatus using such reinforced hoses is taken in tow or is subjected to a strong tidal current in the ocean, a strong external force is applied to the frame body from a specified direction, so that the reinforced hoses forced into the initial bent posture by means of the straight coupling tends to restore the original linear state. Consequently, a crease with a small radius of curvature is produced in the vicinity of the straight couplings to cause kinking of the reinforced hoses constituting the frame body of the fish breeding apparatus, which may lead to the breakage of the hoses in the worst case.
The applicant has previously proposed in Japanese Utility Model Registration Application Laid Open No. 57-36,867 (Japanese Utility Model Registration Application No. 55-111,624) a fish breeding apparatus which can fully tolerate the towing and tidal current.
As shown in FIG. 1, this fish breeding apparatus is so constituted that rod-shaped reinforced elastic members 1 to be charged with a gas are interconnected by means of bent couplings 2 to form a frame body 3 in a polygonal shape having 4-30 sides, in this example, in a hexagonal form; a fitting portion 5 for mooring rope 4 is provided on each bent coupling 2; and nets 6 are hung from the frame body 3 of the fish breeding apparatus.